<!-- Licensed under a BSD license. See license.html for license -->
<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes">
    <title>Three.js - WebXR - Point to Select w/Move</title>
    <style>
    html, body {
        height: 100%;
        margin: 0;
    }
    #c {
        width: 100%;
        height: 100%;
        display: block;
    }
    </style>
  </head>
  <body>
    <canvas id="c"></canvas>
  </body>
<!-- Import maps polyfill -->
<!-- Remove this when import maps will be widely supported -->
<script async src="https://unpkg.com/es-module-shims@1.3.6/dist/es-module-shims.js"></script>

<script type="importmap">
{
  "imports": {
    "three": "../../build/three.module.js",
    "three/addons/": "../../examples/jsm/"
  }
}
</script>

<script type="module">
import * as THREE from 'three';
import {VRButton} from 'three/addons/webxr/VRButton.js';

function main() {
  const canvas = document.querySelector('#c');
  const renderer = new THREE.WebGLRenderer({canvas});
  renderer.xr.enabled = true;
  document.body.appendChild(VRButton.createButton(renderer));

  const fov = 75;
  const aspect = 2;  // the canvas default
  const near = 0.1;
  const far = 50;
  const camera = new THREE.PerspectiveCamera(fov, aspect, near, far);
  camera.position.set(0, 1.6, 0);

  const scene = new THREE.Scene();
  // object to put pickable objects on so we can easily
  // separate them from non-pickable objects
  const pickRoot = new THREE.Object3D();
  scene.add(pickRoot);

  {
    const loader = new THREE.CubeTextureLoader();
    const texture = loader.load([
      'resources/images/grid-1024.png',
      'resources/images/grid-1024.png',
      'resources/images/grid-1024.png',
      'resources/images/grid-1024.png',
      'resources/images/grid-1024.png',
      'resources/images/grid-1024.png',
    ]);
    scene.background = texture;
  }

  {
    const color = 0xFFFFFF;
    const intensity = 1;
    const light = new THREE.DirectionalLight(color, intensity);
    light.position.set(-1, 2, 4);
    scene.add(light);
  }

  const boxWidth = 1;
  const boxHeight = 1;
  const boxDepth = 1;
  const boxGeometry = new THREE.BoxGeometry(boxWidth, boxHeight, boxDepth);

  const sphereRadius = 0.5;
  const sphereGeometry = new THREE.SphereGeometry(sphereRadius);

  function makeInstance(geometry, color, x) {
    const material = new THREE.MeshPhongMaterial({color});

    const cube = new THREE.Mesh(geometry, material);
    pickRoot.add(cube);

    cube.position.x = x;
    cube.position.y = 1.6;
    cube.position.z = -2;

    return cube;
  }

  const meshToMeshMap = new Map();
  [
    { x:  0, boxColor: 0x44aa88, sphereColor: 0xFF4444, },
    { x:  2, boxColor: 0x8844aa, sphereColor: 0x44FF44, },
    { x: -2, boxColor: 0xaa8844, sphereColor: 0x4444FF, },
  ].forEach((info) => {
    const {x, boxColor, sphereColor} = info;
    const sphere = makeInstance(sphereGeometry, sphereColor, x);
    const box = makeInstance(boxGeometry, boxColor, x);
    // hide the sphere
    sphere.visible = false;
    // map the sphere to the box
    meshToMeshMap.set(box, sphere);
    // map the box to the sphere
    meshToMeshMap.set(sphere, box);
  });

  class ControllerPickHelper extends THREE.EventDispatcher {
    constructor(scene) {
      super();
      this.raycaster = new THREE.Raycaster();
      this.objectToColorMap = new Map();
      this.controllerToObjectMap = new Map();
      this.tempMatrix = new THREE.Matrix4();

      const pointerGeometry = new THREE.BufferGeometry().setFromPoints([
        new THREE.Vector3(0, 0, 0),
        new THREE.Vector3(0, 0, -1),
      ]);

      this.controllers = [];

      const selectListener = (event) => {
        const controller = event.target;
        const selectedObject = this.controllerToObjectMap.get(event.target);
        if (selectedObject) {
          this.dispatchEvent({type: event.type, controller, selectedObject});
        }
      };

      const endListener = (event) => {
        const controller = event.target;
        this.dispatchEvent({type: event.type, controller});
      };

      for (let i = 0; i < 2; ++i) {
        const controller = renderer.xr.getController(i);
        controller.addEventListener('select', selectListener);
        controller.addEventListener('selectstart', selectListener);
        controller.addEventListener('selectend', endListener);
        scene.add(controller);

        const line = new THREE.Line(pointerGeometry);
        line.scale.z = 5;
        controller.add(line);
        this.controllers.push({controller, line});
      }
    }
    reset() {
      // restore the colors
      this.objectToColorMap.forEach((color, object) => {
        object.material.emissive.setHex(color);
      });
      this.objectToColorMap.clear();
      this.controllerToObjectMap.clear();
    }
    update(pickablesParent, time) {
      this.reset();
      for (const {controller, line} of this.controllers) {
        // cast a ray through the from the controller
        this.tempMatrix.identity().extractRotation(controller.matrixWorld);
        this.raycaster.ray.origin.setFromMatrixPosition(controller.matrixWorld);
        this.raycaster.ray.direction.set(0, 0, -1).applyMatrix4(this.tempMatrix);
        // get the list of objects the ray intersected
        const intersections = this.raycaster.intersectObjects(pickablesParent.children);
        if (intersections.length) {
          const intersection = intersections[0];
          // make the line touch the object
          line.scale.z = intersection.distance;
          // pick the first object. It's the closest one
          const pickedObject = intersection.object;
          // save which object this controller picked
          this.controllerToObjectMap.set(controller, pickedObject);
          // highlight the object if we haven't already
          if (this.objectToColorMap.get(pickedObject) === undefined) {
            // save its color
            this.objectToColorMap.set(pickedObject, pickedObject.material.emissive.getHex());
            // set its emissive color to flashing red/yellow
            pickedObject.material.emissive.setHex((time * 8) % 2 > 1 ? 0xFF2000 : 0xFF0000);
          }
        } else {
          line.scale.z = 5;
        }
      }
    }
  }

  const controllerToSelection = new Map();
  const pickHelper = new ControllerPickHelper(scene);
  pickHelper.addEventListener('selectstart', (event) => {
    const {controller, selectedObject} = event;
    const existingSelection = controllerToSelection.get(controller);
    if (!existingSelection) {
      controllerToSelection.set(controller, {
        object: selectedObject,
        parent: selectedObject.parent,
      });
      controller.attach(selectedObject);
    }
  });

  pickHelper.addEventListener('selectend', (event) => {
    const {controller} = event;
    const selection = controllerToSelection.get(controller);
    if (selection) {
      controllerToSelection.delete(controller);
      selection.parent.attach(selection.object);
    }
  });

  function resizeRendererToDisplaySize(renderer) {
    const canvas = renderer.domElement;
    const width = canvas.clientWidth;
    const height = canvas.clientHeight;
    const needResize = canvas.width !== width || canvas.height !== height;
    if (needResize) {
      renderer.setSize(width, height, false);
    }
    return needResize;
  }

  function render(time) {
    time *= 0.001;

    if (resizeRendererToDisplaySize(renderer)) {
      const canvas = renderer.domElement;
      camera.aspect = canvas.clientWidth / canvas.clientHeight;
      camera.updateProjectionMatrix();
    }

    let ndx = 0;
    for (const mesh of meshToMeshMap.keys()) {
      const speed = 1 + ndx * .1;
      const rot = time * speed;
      mesh.rotation.x = rot;
      mesh.rotation.y = rot;
      ++ndx;
    }

    pickHelper.update(pickRoot, time);

    renderer.render(scene, camera);
  }

  renderer.setAnimationLoop(render);
}

main();
</script>
</html>

